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Type: Artigo de periódico
Title: Conformational Study Of (8alpha,8'beta)-bis(substituted Phenyl)-lignano-9,9'-lactones By Means Of Combined Computational, Database Mining, Nmr, And Chemometric Approaches.
Author: Kiralj, Rudolf
Ferreira, Marcia M C
Donate, Paulo M
da Silva, Rosangela
Albuquerque, Sergio
Abstract: Beta-(3,4-Methylenedioxybenzyl)-gamma-butyrolactone (MDBL) and (-)-hinokinin (HK) were obtained by partial synthesis and characterized by 1H NMR and computational methods (conformational analysis, molecular modeling, structural data mining and chemometrics). Three conformers were detected for MDBL and nine were found for HK. The energy differences are around 1 and 2 kcal mol(-1) and rotation barriers are less than 3 and 5 kcal mol(-1) for MDBL and HK conformers, respectively. The geometries of these conformers, obtained from semiempirical PM3 and density functional theory (DFT) B3LYP 6-31G** calculations agree satisfactorily with 1H NMR data (vicinal proton-proton coupling constants) and structures retrieved from the Cambridge Structural Database (torsion angles). DFT combined with some variants of the Haasnoot-de Leeuuw-Altona equations gives the best predictions for the coupling constants. The molecular conformation of MDBL, of HK, and of related systems depends not only on intramolecular interactions but also on crystal packing forces and solvent-solute interactions, in particular hydrogen bonds and polar interactions. Hydration favors more stable HK conformers, which can be important for their behavior in chemical and biological systems.
Subject: 4-butyrolactone
Databases, Factual
Magnetic Resonance Spectroscopy
Models, Molecular
Molecular Conformation
Quantum Theory
Rights: fechado
Identifier DOI: 10.1021/jp066746m
Date Issue: 2007
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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